Comminuting apparatus



3 Sheets-Sheet l COMMINUTING APPARATUS R. W. DUYCKINCK ETAL INVENToRs. P055?? m4 @wmf/#Cl A TTORA/E Y Nov. 15, 1966 Filed Feb. 17. 1964 Nov. 15, 1966 R. w. DUYCKINCK ETAL COMMINUTING APPARATUS 3 Sheets-Sheet 2 Filed Feb. 17, 1964 Fig-2.

INVENTORS. P05597- W UVCK//VCK BY Pfff/Q /@CH Nov. 15, 1966 R. w. DUYcKlNcK ETAL 3,285,523

COMMINUTING APPARATUS 5 Sheets-Sheet 5 Filed Feb. 17, 1964 IN VEN TORS.

ATTORNEY United States Patent O 3,285,523 CMMINUTING APPARATUS Robert W. Duyckinck, New Providence, and Peter Darroch, Elizabeth, NJ., assignors to Slick Industrial Company, Summit, NJ., a corporation of Delaware Filed Feb. 17, 1964,' Ser. No. 345,169 11 Claims. (Cl. 241-53) This invention relates to the comminution of particulate matter and particularly to an improved construction for machines for effecting material comminution by high speed rotary action.

Conventionally available pulverizing machines employing high speed rotary action are usually the compromise product of conflicting design considerations relative to desired comminution action or desired separating action. Such units are normally designed to be possessed of one particularly desirable or advantageous attribute in either the comminuting or separating sections thereof in accord with a particular controlling consideration relevant to its intended use and such is usually attained at the expense of other generally desirable attributes or actual attendant disadvantages which are tolerated by the user thereof. Such compromise of design considerations has been of particular concern in the generally intermediate area of particle sizing falling between a medium fine grind and an ultra fine grind. 'Fhere has long been a demand for a high capacity pulverizer capable of producing, at high grinding efficiencies, selectively sized products from a wide intermediate range of available output sizes thereof and which would be of simple inexpensive construction and of an enduring wear resistant character.

The subject invention may be briefly described as an improved construction for high speed rotary action pulverizing machines incorporating a markedly improved and positively directed transport system which serves to discretely convey comminuted material from a locus of pulverization into a locus of selective particle separation and to repetitively reconvey oversize particulate matter through the locus of pulverization.

In its broad aspects, the subject invention is related to the class of pulverizing machines of the general type illustrated in Sheldon United States Patent 2,922,589, wherein the pulverizing means and the product classification or separation means are disposed in a common grinding chamber but are provided with separate drives therefor.

Among the advantages attendant the subject invention is the provision of a directed flow of comminuted material that is essentially discrete in nature and minimizes random particle movement; the provision of an internal transport system that is independent of gravity for its maintenance; the minimization, if not avoidance, of surge loading through positive and regular return of oversize particles to the locus of pulverization for further reduction without interference with that portion of the transport system conveying particulate matter from the locus of pulverization to the locus of separation; a lack of tolerance criticality with consequent permitted economies of manufacture; ease of maintenance both insofar as routine cleaning and feed load adjustment are concerned and consequent minimization of down time with reduction in operating costs.

ICC

The principal object of this invention is the provision of an improved construction for high speed rotary action pulverizing machines.

Another object of this invention is the provision of an 'improved construction for comminuting machines of high capacity capable of producing, at high grinding eiliciencies, selectively sized products from a wide range of available output sizes thereof and of a simple inexpensive construction that aifords appreciable manufacturing and operating economies.

Other objects and advantages of the invention will become apparent from the following disclosure and claims and from the appended drawings which disclose the principles of the invention as the same are embodied, by way of illustrative example, in presently preferred constructions of high speed rotary action pulverizing machines.

Referring to the drawings:

FIGURE 1 is a side elevational View, partly broken away, of the essentials of an impact pulverizing machine incorporating the subject invention.

FIGURE 2 is an enlarged oblique schematic View, partially broken away, generally illustrating the positional relationship of the major machine components incorporated in the subject invention.

FIGURE 3 is an enlarged schematic View, in the nature of a simplified vertical section, showing the positional relationship of the major grinding chamber components in a slightly modified construction incorporating the principles of the invention.

FIGURE 4 is a sectional view of the baille members.

FIGURE 5 is a sectional view on the line 5 5 of FIGURE 4.

FIGURE 6 is a sectional view of an alternative construction embodying the subject invention.

FIGURE 7 is a schematic sectional view illustrative of another alternative embodiment of the invention.

FIGURE 8 is a pair of graphical presentations of typical results obtained in the grinding of sugar in a unit of the type illustrated in FIGURES 1 and 2.

Referring to the drawings and particularly to FIGURES 1-3 thereof, there is provided a pulverizing machine incorporating a selectively shaped grinding chamber 2 of appreciably limited longitudinal extent disposed within a cylindrical side wall housing 4. The grinding chamber 2 is effectively terminated at one end thereof by high speed rotary action material comminuting means of essentially planar conguration generally designated 10, and at the other end in a generally annular conguration incorporating a radial flow classifying means, generally designated 12. The radial flow classifying means is preferably in the nature of a truncated conically shaped rotor having its apex disposed parallel to the comminuting rotor 10. as illustrated, the apex of truncated particle classifying means is of appreciably lesser radial extent than said material comminuting means and is disposed appreciably below the uppermost surface of the grinding chamber thereby serving to form, in part, the generally annular configuration for one end of the grinding chamber 2 as mentioned above.

As will be later described in greater detail, a gaseous carrier, suitably and usually air, for the comminuted particulate matter is preferably admitted to the grinding chamber 2 through the primary air intake manifold assembly 6 disposed beneath the rotatable comminuting means and is exhausted therefrom through the classifying means 12, the outlet manifold assembly 74 and outlet conduit 8 by, for example, incorporation of the unit in a suitable differential pressure system, preferably associated with auxiliary dust collecting means (not shown) to effect separation of the comminuted particulate matter from the gaseous carrier.

As illustrated, the presently preferred construction for the high speed rotary action comminuting means 10 includes a disk-like rotor 14 mounted on the upper terminus of a drive shaft and provided with a plurality of perpendicularly disposed pin members 16 removably secured thereto adjacent its periphery. The rotor drive shaft 20 is rotatably mounted in a suitable bearing 22 which, in turn, is conveniently supported by `one or more webs 24 forming a part of the primary air intake manifold assembly 6. The comminuting rotor .14 is conveniently driven at any desired preselected speed within an available range thereof by an independent drive system which convention-ally may include a drive motor 26 together with pulleys 28 and 30 and a drive belt 32 disposed in the base portion 34 of the illustrated unit. As illustrated, the web bearing supports 24 may constitute an integral part of the primary air intake manifold assembly 6 which may suitably be in the nature of a casting 36 disposed intermediate the lower terminus of the grinding chamber side wall housing 4 and the aforementioned base 34 of the subject machine.

The cylindrical side wall housing 4 that serves to partially define the grinding chamber 2 is preferably removably mounted on the upper portion of the air intake manifold Aassembly casting 36 an-d has its side wall suitably apertured adjacent to the locus of comminution as defined -by the path of travel -of the pins 16, as at 60, to form an inlet for material which is to be comminuted. Any suitable type of material feed, adapted to maintain a selected feed rate may be used as, for example, a screw type conveyor 62 and an associated hopper 64.

As illustrated in FIGURES 1-3, the illustrated and presently preferred construction for the rotatable classifying means 12 includes a peripherally vaned rotor 40 mounted `on the dependent end of a drive shaft 42 disposed coaxially with the comminution rotor drive shaft 20 and which is rotatably supported in a suitable bearing `44. The vaned classifying rotor 40 is adapted to be driven at a preselected and predetermined speed, in accordance with the desired particle size to be delivered, by an independent drive system which may include, by way of illustrative example, a drive motor 46, a variable block a possible straight line bypass passage or channel for particulate matter that is necessarily formed by the required clearance space between the ends of the vanes 68 and the adjacent housing surface.

The envelope represented by the angular disposition of 'the tips of the vane members 68 is complementally continued by the selective contouring of the adjacent surfaces of the annular dependent end portion 70 of the casting 72, as 'at 78, so as to effectively provide an unbroken envelope of essentially truncated conical configuration. The generally sloping surface 78 of the casting 72 is merged, as by the smooth curved portion 80, into an essentially linear section 82 parallel to the surface of the comminuting rotor 14 and which terminates adjacent the side wall portion of the housing 4.

As is illustrated, the casting 72 and the various elements associated therewith, including the c-lassifying means 12, are desirably constructed so as to be removably securable, as ya unit, to the housing 4. More specifically, the upper end of the housing 4 .and the casting 72 are provided with peripheral flanges 84, 86. The flanges 84, 86 are so constructed as to selectively permit abutting interfacial contact with an interposed gasket in operatively carrier-tight relation or the interposiion of spacer elements 88 (as shown in FIGURE 3) of graduated size so as to provide for the inclusion of a secondary air inlet opening of predetermined extent therebetween. Such construction provides not only for ready separa-bility for cleaning purposes but also serves to provide, when desired or required, a secondary air inlet opening of selectable magnitude in accordance with i lthe dictates ofthe particular lmaterial undergoing comspeed transmission or drive unit of conventional conl -struction and generally designated 48, pulleys 50 and 52 and drive belt 541. The variable speed transmission or drive unit 48 may be of any suitable construction to provide for the preselection of rotor speeds Within a predetermined range thereof and may constitute, for example, a construction such -as that disclosed in detail in the aforementioned Sheldon Patent No. 2,922,589.

As best shown in FIGURES 1-3, the classifying rotor 40 is preferably of a truncated conical configuration having at its apex a planar portion 66 disposed in spaced parallel rel-ation with the surface of the comminuting rotor '14. Peripherally mounted on the planar portion 66 are a plurality of angularly disposed and spaced vane members 68. The upper ends of the vane members 68 are disposed in close parallel proximity with the Iannularly shaped dependent end portion 70 of a selectively contoured casting 72 which serves to partially define the grinding chamber configuration as well as to define the outlet manifold 74 for said grinding chamber.

More specifically, the dependent end portion 70 of the casting is provided with an annular dependent ange 76 disposed to the rear or the downstream side of the upper ends of the vanes 68 which serves to effectively minution.

Disposed within the selectively shaped grinding chamber 2 as described above is an annular isolating baffle member 90, preferably in the nature of a truncated conically shaped shell, :having its inner surface, or at least an appreciable portion thereof, disposed substantially parallel to the periphery of the vaned classifier, As shown in FIGURES 1, 3, 4 and 5, the annular isolating bafile may, for smaller size units, be in the nature of a casting having its upper an-d lower ends suitably rounded as at 94, 96 and selectively shaped so `as to have its dependent portion spaced at a greater distance from the vaned classifier 40l that the upper portion thereof. For larger size units and as illustrated in FIGURE 2, the annular isolating baffle may be formed of planar rolled stock of markedly reduced thickness. In each instance, however, the annular isolating baffle 98 is positioned roughly midway between the side Wall housing 4 and the vaned classifying rotor 46' and also roughly midway between the planar surface 82 of the casting 72 and the comminuting rotor 14. As illustrated, the annular isolating 'baffle 90 is of such longitudinal dimension as to extend over the major portion of the longitudinal extent of the grinding chamber 2 and to have its dependent end interposed in .any possible straight line path drawn from any portion of the pins 16 to and through any portion of the vanes 68 of the classifying rotor to thereby prevent direct `displacement of comminuted particulate matter through the classifier and to assure the transport of oversize material from the locus of separation back through the locus of pulverization.

The annular isolating baffle member 9) is selectively positioned as above specified by a plurality yof axial baffle members 100 in the nature `of radially extending webs which are secured to the inner wall of the housing 4. As best shown in FIGURES 2, 4 and 5, the axial baffle members 100 are preferably selectively shaped so as to provide a curved surface 102 disposed in the path of carrier motion .adapted to effect a marked change of direction of the gaseous carrier and the comminuted particulate material carried thereby, as will be explained in detail at a later point in this specification.

In operation of the subject unit, the outlet manifold 8 is connected to a suction source (not shown) to draw air or other gaseous carrier with gradually increasing velocity from the air intake manifold 6, through the passage disposed intermediate the undersurface of the rotor 14 and the adjacent converging surface 37 of the air inlet manifold casting 36. Coincidently therewith, the fan action due to the high operating speed ofthe comminuting rotor 14 markedly increases the vel-ocity of such carrier and effects a swirling or rotative displacement thereof with gradually increasing velocity as said carrier approaches the rotor periphery. The material to be comminuted is fed at a preselected rate into the grinding chamber 2 at a point adjacent the periphery of the comminuting rotor 14 through the aperture 60 from the feed hopper 64 by the screw conveyor mechanism 62, to be comminuted, in the FIGURES 1-3 embodiment, by the impact thereofwith the rapidly moving pins 16. The particulate matter so comminuted is entrained in the swirling carrier that is introduced into the grinding chamber 2 intermediate the periphery of the rotor 14 and the side wall housing 4, supplemented by that portion of the carrier conveying oversize material back through the locus -of pulversization. Such swirling carrier, due to the velocities involved, will be selectively disposed adjacent the side wall 4 of the grinding chamber, its speed being supplemented by the fan action of the rotor 14 and pins 16, and will gradually rise in a spiral path under the infiuence of the applied pressure differential, until it encounters the axial baffle members As the swirling carrier bearing the entrained particulate matter encounters the axial bafiie members 100, the impingement thereof with the dependent end of the curved surfaces 102, serves to effect a marked change of both Speed and direction thereof and a displacement of the entrained material to :a path substantially :parallel to the longitudinal axis of the grinding chamber 2 and with greatly minimized swirling or rotative action. This modified flow continues upward over the upper end of the annular isolating baffle 90 and is guided thereby and by the surfaces 82 and 80 in the undersurface of the casting 72 into the annular channel disposed intermediate the classifying rotor 40 and the inner facing surface 92 of the baflie 90.

As is conventional in radial flow classifying rotors, the speed of rotation of the vaned classifying rotor 40 is adjusted to permit comminuted material up to -a predetermined size of grind to pass through the rotating blades and into the outlet manifold 74 under the influence of the suction of air from the outlet conduit 8 and at the same time selectively reject, by centrifugal action and impact, the heavier coarse material.

It will now be apparent that the carrier entrained comminuted material, both fine and coarse, approaches the separator or classifier blades 68 on a substantially smooth essentially uniplanar and confined course with reduced velocity and that the outer edges of the blades 68 are in the nature of an extension of the casting surface 7 0. Such presentation of the entrained particulate material to the locus of separation is recognized as highly desirable and results in markedly improved classifier operation and selective classification in the subject unit.

In operation of the subject unit, the oversize particles rejected by the classifying means continue their displacement toward the surface of the high speed rotor 14. As the rejected particles approach the rotating comminuting disk 14 its centrifugal pumping action supplements the swirling action induced by the classifier rotor and, in combination with the dependent edge of the annular isolating baffie 90, forcefully directs the oversize particles outwardly toward the rapidly moving pulverizing pins 16 to be further comminuted. These particles, as further cornminuted, are again picked up by the gaseous carrier and again presented to the classifier means for acceptance or rejection in the manner `described above.

It will now be apparent from the foregoing to those skilled in this art that the subject construction affords a markedly improved transport system for the material being comminuted wherein transport paths are positively delineated, controlled and guided and wherein particle entr-ainment is advantageously effected in a swirling type of flow after which a marked change of direction is effected to secure a more advantageous lineal type of flow for classification purposes. Additionally, the inclusion of the annular isolating baffle member serves not only to effectively isolate portions of the grinding chamber wherein selective flow is taking effect from the deleterious fioW modifying effects of other grinding chamber components but also functions to guide and direct the specified flow paths and to prevent direct displacement of particulate matter from the pins 16 through the vanes 68.

It is to be understood that while the presently preferred embodiments of the invention, as described heretofore, employ comminuting means in the nature of a high speed rotor having a plurality of pins peripherally mounted thereon, other types of comminuting means employing high speed rotary action may be employed and wherein comminution may be effected by impact or by a combination of impact and attrition. For example, a comminuting rotor as shown and described in Sheldon U.S. Patent No. 2,922,589 could be utilized.

Referring now to FIGURE 6, there is illustrated one modified construction `for Va grinding chamber 2 incorporating theprinciples of the subject invention. In this modied construction there is provided an outlet manifold 150 formed by a casting 130 whose undersurface defines, in part, one end of the grinding chamber 2. Casting 130 is essentially of the same configuration as casting 72 described earlier in conjunction with the previous embodiments and presents a peripheral fiat surface 131, an adjacent curved surface 172 4and a dependent portion of conical configuration that merges with the upper end of the vanes of the rotatable classifying rotor 118.

The outlet manifold castin-g 130 and classifier assembly `are conveniently hinged to the cylindrical side wall housing as by brackets 194 and 196 pivoted at 132. In this modied section as shown in FIGURE 6 suitable means, as for example, spacer washers 201, are positionable intermediate the adjacent extending flanges of the casting and rside wall housing 110 on securing bolts 202 to provide an -annular air inlet passage 203 for the entry of air or other `gaseous carrier that is to be em- -ployed.

Such location of an air inlet passage 203 at the upper end of the grinding chamber 2 can serve as a secondary air inlet as mentioned earlier in conjunction with the FIGURES 1-3 embodiments or can, ias illustrated in FIG- URE 6, serve as the sole air inlet. For example, as shown in FIGURE 6, an imperforate base 128 underlies the comminuting rotor 116. In order to provide for an outward flow of gaseous carrier on the underside of the comminuting rotor 116 to prevent, inter alia, accumulation of particulate matter thereunder, the rotor 116 is provided with a plurality of spaced apertures 124 having the sides outwardly tapered in the direction of the bottom of the disk to promote a downward and subsequently, radially outwardly directed flow of gaseous carrier toward the rotor `periphery.

In operation of the subject unit, material to be pulverized is introduced into the grinding chamber through inlet adjacent the periphery of the comminuting rotor 116 by a screw feed assembly. Air or other -gaseous carrier enters through the annular opening 203 and is directed by the straight and curved surfaces 131 and 172 and the annular isolating bafe 182 in a direction substantially parallel and past the outer periphery of the blades of separator 118. At this point, a portion of the carrier and t-he particu-late matter entrained therein is diver-ted and passes through the separator blades under `the inlluence of suction from the outlet manifold 150. The remainder of the carrier bearing the oversize material continues to move downwardly toward the surface of the comminuting rotor 116.

Adjacent the surface of the rotor 116 a portion of the downwardly directed air stream is diverted, due to the pumping action of the rotor, radially outwardly and in a swirling path through the locus of pulverization as dened by the pins 120, while a portion thereof passes through the apertures 124 land is thence displaced radially outward-ly in .a swirling path to pass upwardly adjacent the locus of pulverization at the rotor periphery.

As the carrier passes the locus of pulverization, the pulverized material is entrained therein and moves upwardly in substantially circular path intermediate the side walls of the housing 4 and the annular isolating baille 182 und-er the influence of its momentum and the pumping actions of the comminuting rotor 116. As was the case in the earlier embodiment, the axial baflles 188veffect a marked change of direction and reduction in velocity of the car-rier :and convert its circular path of travel to a substantially vertical and :lineal path adjacent the side wall. As the now substantially upwardly moving carrier stream reaches the upper portion of the chamber and start to change direction, the carrier and entrained material merges with new incoming air entering through the annular opening 203 and is directed again by the curved surface 172 in the manner heretofore described.

FIGURE 7 is illustrative of a further alternative embodiment of the grinding chamber components of a comminuting unit incorporating the principles of this invention. As here shown, there is provided a comminuting rotor 300 in the nature of .a disk 302 having a plurality -of rectangular blocks 304 mounted on the periphery thereof. The blocks 304, in association with the adjacent breaker surface liner 306 mounted on the side wall 308 of the grinding chamber effects comminution by means of both impact and attrition. Preferably a shroud ring 310 is mounted on top of the blocks 304 and is firmly secured thereto in order to provide for the requisite mechanical strength needed because of the high operating speeds involved.

Associated with the above-described comminuting means is a radial flow classifying means included within the grinding chamber in the nature of la vaned rotor 312 disposed in coaxial alignment with the longitudinal axis of the comminuting rotor. Positioned intermediate the periphery of the classifying means 312 and the side wall 308 of the grinding chamber is an annular isolating baille 314 having its inner surface positioned substantially parallel to the classifying rotor Vanes. As was the case in the previously described embodiments, the annular isolating baille 314 is supported by a plurality of axial baille members 316 secured to the side wall 308 of the grinding chamber. As was the case wit-h the FIGURE 6 embodiment, primary air as the gaseous carrier is introduced through an :annular opening 318 intermediate the outlet manifold casting 320 andthe end of the side Wall 308 of the Igrinding chamber rand the rotor 302 is apertured as at 322 to prevent accumulation of particulate matter therebeneath.

The following comparative test data for various materi-als clearly demonstrates the versatility of the subject construction and the improved results that ilow therefrom as compared with certain commercialvpulverizers of the following general types.

Machine A-improved unit as described herein Machine B-screen hammer mill of the general type illustrated in United States Patents 1,711,464 and 2,128,194

Machine C-a 13" unit of the general type illustrated in she-mon. UnitedStates Patent 2,922,589

Machine D-a unit of the general type shown in Sheldon United States Patent 2,5 5 2,596

Machine B Machine A Eil. (#HP-hr.) based on total motor 1oad 1. 2 2. 44 Percent through 150 on 23. 6 93. 6

NO. 2-TOBACCO-PREGROUND 6 MESH MAX.; 30%

THROUGH -7%% THROUGH 200 NO. 4LIMESTONE-8 MESH MAX.; 12 MESH MIN.

Machine B Machine A Eff. (#llHP-hr.) based'on total motor load. 85 96. 7 Percent through on 99. 19 99. 57 Percent through 200 on 89. 81 88. 95 Percent through 325 on 68.79 67. 52

NO. -SUGAR-MEDIUM FINE GRANULATED Machine C Machine A Err. (#/HP-hr.) based on total motor 10ML 37. 4 57. 3 Percent through 140 on 99.32 99.88 Percent through 200 on 98. 25 99. 33 Percent through 325 on 92. 48 93. 52

Still other comparative test results include the following.

Machine A produced 4.8#/HP-hr. of bismuth formic iodide to an unweighrable trace on mesh while Machine B produced 8.5#/HP-hr. `to 93.4% through 120 mesh.

On a rubber chemical, Machine A produced 1l1#/ HP-hr. to 99.7% through 200 mesh while Machine B produced only 50#/HP-hr. of equivalent vyield material.

On limestone, Machine A produced 204.#/HP-hr. to 95.6% through 100 mesh whereas Machine B produced only l54#/HP-hr. to 95.0% through a similar mesh.

On a resin known as Blendex 301, Machine A produced 42.3.#/HP-hr. to 94.7% through 40 mesh, whereas Machine B produced only 23.5 #/HP-hr. to 94.3% through 40 mesh.

Still other tests were made on sugar and on this product Machine A produced l35.2#/HP-hr. to 90.64% through 200 mesh, whereas Machine C produced only 96.2#/HP-hr. to 88.9% through 200 mesh. Machine A also produced l8.6#/HP-hr. to a 36 micron maximum particle size, whereas Machine D produced 14.2#/HP-hr. for a similar maximum particle size.

In addition to the above, Machine A produced 66.0#/ HP-hr. to 94.7% through 325 mesh, while Machine D produced only 50.0#/HP-hr. for equivalent percentile mesh material.

FIGURE 8 lgraphically demonstrates the perform-ance characteristics of the subject unit on sugar at various separator speeds and signicantly demonstrates the broad band Versatility of the subject matter of this invention.

Having thus described our invention, we claim:

1. In comminuting apparatus wherein a gaseous carrier is employed to transport particulate matter cornminuted therein, a generally cylindrical grinding chamber bounded at one end by planar rotatable comminuting means disposed perpendicular to the longitudinal axis of said chamber and terminating at the other end thereof in a generally annular configuration, said annular configuration formed in part by rotatable radial flow classifying means having an apex dependently disposed in coaxial proximity with said comminuting means and carrier transport path defining means including an larcuately shaped intermediate segment smoothly connecting the upper terminus of said grinding chamber with the periphery of said classifying means, annular isolating baille means disposed intermediate said classifying means and the grinding chamber wall and intermediate said grinding chamber ends and a plurality of axial baille members disposed intermediate said annular isolating baille means and said grinding chamber Walls for changing the velocity and direction of displacement of said carrier from a generally circular path in planes substantially perpendicular to the longitudinal axis of said chamber adjacent to said rotatable comminuting means to a substantially lineal path parallel to said axis at locations remote therefrom.

2. Pulverizing apparatus as set forth in claim 1 wherein said rotatable comminuting means comprises a disclike member having a plurality of particle impacting means mounted adjacent to the periphery thereof.

3. In comminuting apparatus wherein a gaseous carrier is employed to transport particulate matter comminuted therein, a generally cylindrical grinding chamber having a carrier outlet at one end thereof, a radial flow classifier associated with said air outlet to selectively reject oversized pulverized material, rotatable comminuting means disposed remote from said carrier outlet, annular isolating baffle means positioned intermediate the working perimeters of said classifying and comminuting means to effect a discrete return path between said classifier and comminuting means for classifier rejected material, the inside surfaces of the end of said housing associated with said outlet being smoothly curved to define with said baille means a smooth main flow path for said carrier and particulate matter entrained therewith between said comminuting means and classifier.

4. The combination as set forth in claim 3 including axial baille means disposed intermediate saidv annular isolating baille means and said grinding chamber defining side walls to effect a change in direction and velocity of said carrier in its transport from said comminuting means to said classifying means.

5. An improved comminuting apparatus construction comprising a generally cylindrical housing having a side wall and one end wall of annular configuration and centrally apertured to form a gaseous carrier outlet therein, a radial ilow classifier rotatably mounted in said outlet, rotary type comminuting means mounted in said housing in spaced relation with said classifier, said end Wall having an inner surface curved to present a substantially smooth main carrier approach flow path to said classifier,

axial baille means positioned adjacent said housing side wall to induce a lineal flow of carrier therein, and isolating baille means disposed in predetermined spaced relation intermediate the perimeters of said classifier and comminuting means to effect discrete carrier flow paths from said comminuting means to said classifier means and from said classifier means to said comminuting means.

6. In comminuting apparatus wherein a gaseous carrier is employed to transport particulate matter, a grinding chamber having a generally cylindrical side wall bounded at one end by planar comminuting means and terminating at the other end thereof in generally annular configuration, said annular configuration formed in part by rotatable radial flow classiying means having an apex dependently disposed in proximity to said comminuting means, annular carrier flow path dening means including an arcuately shaped intermediate segment smoothly connecting the terminus of said grinding charnber with a basal segment that peripherally merges with said classifying means, an isolating annular bale ring disposed in surrounding and substantially parallel spaced relation to said classifying means and positioned intermediate said classifying means and the grinding chamber wall for maintaining a discretely separated ilow of gaseous carrier from the comminuting means to the classifying means and from the classifying means to said comminuting means, and a plurality of vertical baffle members disposed intermediate said annular baille and said grinding chamber walls for effecting a marked change in direction of said carrier preparatory to presentation thereof to said classifying means.

7. Comminuting apparatus as set forth in claim 3 wherein said comminuting means comprises a rotatable disc like member having particle impacting means peripherally mounted thereon.

8. Comminuting apparatus as set forth in claim 3 wherein the longitudinal axis of said grinding chamber is vertically disposed.

9. Comminuting apparatus as set forth in claim 3 including an inlet for said carrier disposed adjacent to the undersurface of said comminuting means.

10. Comminuting apparatus as set forth in claim 3 including an inlet for said gaseous carrier disposed adjacent the terminus of said smoothly curved inside surface of said housing.

11. Comminuting apparatus as set forth in claim 3 wherein said comminuting means is adapted to effect material comminution by impact and attrition.

References Cited by the Examiner UNITED STATES PATENTS 3/ 1942 Schwartz 241-58 1/ 1960 Sheldon 241-53 

1. IN COMMINUTING APPARATUS WHEREIN A GASEOUS CARRIER IS EMPLOYED TO TRANSPORT PARTICULATE MATTER COMMINUTED THEREIN, A GENERALLY CYLINDRICAL GRINDING CHAMBER BOUNDED AT ONE END BY PLANAR ROTATABLE COMMUNICATING MEANS DISPOSED PERPENDICULAR TO THE LONGITUDINAL AXIS OF SAID CHAMBER AND TERMINATING AT THE OTHER END THEREOF IN A GENERALLY ANNULAR CONFIGURATION, SAID ANNULAR CONFIGURATION FORMED IN PART BY ROTATABLE RADIAL FLOW CLASSIFYING MEANS HAVING AN APEX DEPENDENTLY DISPOSED IN COAXIAL PROXIMITY WITH SAID COMMINUTING MEANS AND CARRIER TRANSPORT PATH DEFINING MEANS INCLUDING AN ARCUATELY SHAPED INTERMEDIATE SEGMENT SMOOTHLY CONNECTING THE UPPER TERMINUS OF SAID GRINDING CHAMBER WITH THE PERIPHERY OF SAID CLASSIFYING MEANS, ANNULAR ISOLATING BAFFLE MEANS DISPOSED INTERMEDIATE SAID CLASSIFYING MEANS AND THE GRINDING CHAMBER WALL AND INTERMEDIATE SAID GRINDING CHAMBER ENDS AND A PLURALITY OF AXIAL BAFFLE MEMBERS DISPOSED INTERMEDIATE SAID ANNULAR ISOLATING BAFFLE MEANS AND SAID GRINDING CHAMBER WALLS FOR CHANGING THE VELOCITY AND DIRECTION OF DISPLACEMENT OF SAID CARRIER FROM A GENERALLY CIRCULAR PATH IN PLANES SUBSTANTIALLY PERPENDICULAR TO THE LONGITUDINAL AXIS OF SAID CHAMBER ADJACENT TO SAID ROTATABLE COMMINUTING MEANS TO A SUBSTANTIALLY LINEAL PATH PARALLEL TO SAID AXIS AT LOCATIONS REMOTE THEREFROM 